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M Massad

Publications and source records attributed to M Massad.

At least 19 recordsLinked to original sources
PubMed1998

A new rat model to study the correlation of cardiac and skeletal muscle allograft rejection.

As a first step to study the correlation of cardiac and skeletal muscle allograft rejection, we describe a new experimental rat model of simultaneous heterotopic heart and cutaneous maximus muscle flap allotransplant. Brown Norway rats were used as donors and Lewis rats as recipients. No immunosuppression was given. The grafts were revascularized with sequential end-to-side anastomosis of each vascular pedicle to the infrarenal aorta and vena cava. Syngeneic heart and cutaneous maximus muscle grafts remained functional and showed no sign of rejection at 7 days after the transplant. In contrast, both allografts developed severe rejection and functional compromise at 7 days after the transplant. Our experimental model is technically feasible and reproducible and may provide important information about the pattern of rejection of cardiac and skeletal muscle allografts.

Animals↗
PubMed1994

Missile embolization revisited: a rationale for selective management.

Embolization of missiles is an unusual presentation of penetrating trauma. Often the management of these injuries may be quite challenging, and selective management continues to be subject to controversy. We report a case of a bullet embolus to the right ventricle from the internal iliac vein in a 15-year-old boy that was managed with observation. An algorithm for diagnosis and management of this phenomenon mandates exploration of emboli to the aorta and peripheral arteries with repair of the vascular entry site and embolectomy. It also recommends operative intervention for symptomatic venous emboli to the heart and pulmonary circulation. Nonoperative management may be considered in patients with asymptomatic emboli to the right heart or the cerebral and pulmonary circulation.

Adolescent↗
PubMed1992

Prolonged ventilatory support after open-heart surgery.

OBJECTIVES: To characterize the course of open-heart surgery patients who require prolonged (greater than 72 hrs) mechanical ventilation and to define the role and timing of tracheostomy. DESIGN: Retrospective review. SETTING: Cardiac surgery ICU and surgery wards at a university hospital. PATIENTS: All open-heart surgery patients during an 18-month period from January 1988 to July 1989 (n = 581). From this group, 58 patients (9.9%) required prolonged mechanical ventilation. INTERVENTIONS: Study patients (n = 58) were followed through the course of intubation and/or tracheostomy until they were extubated, left the hospital on ventilation, or died. MEASUREMENTS AND MAIN RESULTS: End-points for mortality and complications were determined. Overall mortality rate was 43% in the patients who required prolonged mechanical ventilation. Twenty-eight percent of the 58 patients died within the first 14 days. Of those patients who survived, 55% required an endotracheal tube only and were extubated in less than 14 days; 45% of the patients required tracheostomy. Of those patients who required tracheostomy, five (26%) were eventually extubated, seven (37%) remained mechanically ventilated, and seven (37%) died. The complication rate for endotracheal tubes was 65%; the complication rate for tracheostomy was 37%. CONCLUSIONS: Open-heart surgery patients requiring prolonged mechanical ventilation are a desperately ill subset of cardiac surgery patients. Those patients who survive are either extubated in less than 14 days or require prolonged mechanical ventilation beyond that point. In our opinion, patients should be given 1 wk to recover and one trial of weaning from the ventilator. If this approach fails, then they should undergo elective tracheostomy.

Algorithms↗
PubMed1992

Short-term and long-term results of experimental wrapping techniques for bronchial anastomosis.

Major complications of bronchial anastomoses for either transplantation or sleeve resection include early leak, fistula formation, granulation tissue, and stenosis. To evaluate the impact of technique on these complications, we designed a nonimmunocompromised canine model with a totally ischemic bronchial segment. We wished to discover the prevalence of early and late complications of a telescoping anastomosis and if wrapping techniques modify them. We autotransplanted 25 mm of left main-stem bronchus by telescoping 1 mm of proximal into distal bronchus sutured with interrupted 4-0 polyglactin sutures. The animals were divided into four groups: no wrap; omental pedicle wrap; detached-free omental wrap; and Gelfoam sponge soaked in porcine omental extract. Weekly bronchoscopic studies assessed airway patency. After the animals were put to death at 70 days, the luminal areas of the proximal anastomoses were compared with the origin of the left main bronchus. No air leak, bronchial disruption, or infection occurred in any group at any time. Luminal narrowing occurred in all four groups but was most pronounced in the three groups in which wrapping techniques were used. We conclude that wrapping of a telescoped anastomosis is not necessary to prevent early complications. However, no method completely eliminates stenosis. Further experiments should determine the effects of immunomodulation in this model.

Anastomosis, Surgical↗
PubMed1991

Endoscopic thoracic sympathectomy: evaluation of pulsatile laser, non-pulsatile laser, and radiofrequency-generated thermocoagulation.

We describe a modified technique for percutaneous denervation of the thoracic sympathetic chain by laser to treat selected cases of sympathetic causalgia of the upper extremities. The technique involves transpleural ablation with laser under thoracoscopic guidance through the second or third intercostal space-anterior axillary line. We also compare four different modalities of endoscopic denervation: A xenon chloride excimer laser (308 nm, 35 mJ/pulse, 20 pulses/sec, 2.2 mm catheter tip), CO2 laser (14 W, CW, 2 mm spot size), Nd:YAG laser (88 W, CW, 3 mm spot size), and radiofrequency-generated thermocoagulation (3 W, CW, 2.1 mm catheter tip) by performing bilateral thoracic sympathectomy on 12 mongrel dogs (three dogs each). Criteria analyzed included duration of exposure, power density, total energy output, laser penetration and spread, gross morphology, and scanning electron microscopy (SEM) of the destroyed neural tissue. Total ablation of the inferior segment of the stellate ganglion and the T1-T2 nerve roots by excimer laser required 83 +/1 1 Joules over an exposure period of 118 seconds. Ablation by CO2 and Nd:YAG laser required 153 +/- 13 Joules and 554 +/- 47 Joules delivered over 11 and 6 seconds respectively. In contrast, ablation of the same volume of nerve tissue by RF required 810 +/- 50 Joules over 270 seconds. SEM evaluation revealed that excimer and CO2 laser lesions were narrower in configuration compared to RF and Nd:YAG lesions which showed more lateral spread. The actual depth of penetration per 1 second exposure was similar for Excimer and CO2 (1.5 mm) and RF (1.3 mm), but deeper for Nd:YAG (3 mm).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Ballistic trauma to the abdomen: shell fragments versus bullets.

Two-hundred ninety-nine patients who sustained penetrating ballistic trauma to the abdomen were divided into two groups: Group A consisted of 133 patients with shell fragment injuries from mortar artillery and Group B of 166 patients with bullet injuries from rifles and automatic or semiautomatic weapons. Both groups were analyzed retrospectively in order to compare the extent of injury and outcome. In Group A, the findings at laparotomy were negative in 15 of 133 patients (10%) compared with 9 of 166 patients (5%) in Group B (p less than 0.05). The most commonly injured abdominal organs in Group A were the colon (42%), liver (22%), small bowel (20%), stomach (14%), diaphragm (11%), spleen (10%), major vessels (40%) [corrected], and kidney (9%). The abdominal organs commonly injured in Group B were the colon (50%), small bowel (41%), liver (33%), major vessels (20%), diaphragm (17%), stomach (15%), spleen (15%), and kidney (15%). Associated extra-abdominal injuries were present in 26% of Group A patients and in 21% of Group B patients (p greater than 0.05) [corrected]. Major postoperative complications occurred in 7.5% and 8.4% of the patients in Group A and Group B, respectively (p less than 0.05). Perioperative mortality was 2.3% in Group A versus 7.2% in Group B (p less than 0.01). Our data suggest that high energy bullets to the abdomen cause higher tissue penetration and a greater blast effect than shell fragments.

Abdominal Injuries↗
PubMed1991

Effect of desmopressin acetate on hemorrhage without identifiable cause in coronary bypass patients.

After early hopeful reports, the ability of desmopressin acetate (DDAVP) to substantially reduce post surgical hemorrhage has been questioned. A total of 74 elective coronary bypass patients (Group A) receiving DDAVP (0.3 micrograms/kg) who, in the opinion of the operating surgeon, did not achieve adequate hemostasis after protamine neutralization of heparin were studied. They were compared with 91 age- and sex-matched controls (Group B). Before surgery there was no difference in hematocrit (40.8% vs. 40.3%); bleeding time (5.3 vs. 4.9 sec); platelet count (267 +/- 8 vs. 309 +/- 13 X 10(3)/mm3); fibrinogen (363 vs. 361 mg/dl); or activated clotting time (ACT) (168 +/- 4 vs. 163 +/- 3 sec). Both groups had the same number of grafts (3.3/pt), use of the mammary artery (72%), and average bypass time (124 min). There were also no differences in postbypass ACT (142 +/- 3 vs. 135 +/- 2 sec); platelet count (97 +/- 10 vs. 120 +/- 24 X 10(3)/mm3); and fibrinogen (157 +/- 35 vs. 207 +/- 40 mg/dl). However, postoperative hemorrhage was strikingly different: 1306 +/- 89 vs. 896 +/- 33 ml (P less than .0001). Fifteen patients in Group A bled more than 1.5 liters compared with 4 in Group B. Red cell transfusion rates were 1.23 +/- 0.26 for Group A and 0.35 +/- 0.8 for Group B (P less than 0.005). Sixteen Group A patients received additional blood products (plasma and platelets). The hemorrhage difference remained significant even when these patients were excluded (1098 +/- 57 vs. 896 +/- 34, P less than 0.003). Three Group A patients were re-explored without a bleeding source located.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Contribution of the bronchial circulation to lung preservation.

Short preservation time still severely limits lung transplantation. To determine the effect of bronchial arterial flush preservation, we studied 54 dogs using the isolated perfused working lung model. After baseline measurements, lungs were flushed with lactated Ringer's solution (60 ml/kg at 8 degrees C) by one of three methods: pulmonary artery perfusion, bronchial artery perfusion through a 15 cm closed aortic segment, or simultaneous pulmonary-bronchial artery perfusion. These groups were further subdivided and tested after 0, 4, and 17 hours of storage at 4 degrees C (n = 6 each). Lungs were ventilated (flow rate 140 ml/kg/min; inspired oxygen fraction 0.21) and continuously reperfused with normothermic deoxygenated autologous blood in a closed loop. Measured variables were hemodynamics, aerodynamics, and leukocytes in bronchoalveolar lavage. Survival time was determined from initial reperfusion to failure of the lung to oxygenate. After 0 and 4 hours of storage, there was no significant difference in survival times. After 17 hours, lungs subjected to pulmonary-bronchial artery perfusion survived longer than those perfused via either the pulmonary or bronchial arteries alone (120 +/- 24 versus 38 +/- 14 or 52 +/- 16 minutes; p less than 0.01). Pulmonary artery pressure and resistance in all groups except at failure were never different from baseline values in the intact animal. Shunts in the pulmonary-bronchial artery perfusion groups were closest to baseline at onset (8% +/- 4%) and remained lower throughout reperfusion than in the groups subjected to pulmonary or bronchial artery perfusion alone. After 17 hours, static compliance of pulmonary artery-perfused lungs was worse than baseline (1.1 +/- 0.2 x 10(-2) versus 3.2 +/- 0.7 x 10(-2) L/cm H2O/sec; p less than 0.05), whereas compliance in the pulmonary-bronchial artery perfusion groups remained constant (3.6 +/- 1.5 x 10(-2) L/cm H2O/sec). Elastic work performed by lungs subjected to pulmonary-bronchial artery flushing at onset was significantly lower when these lungs were reperfused immediately (201 +/- 14 versus 295 +/- 35 gm-m/min for pulmonary artery-flushed lungs) or after 4 hours of storage (229 +/- 30 versus 290 +/- 24 gm-m/min for pulmonary artery-flushed lungs). Bronchoalveolar lavage after 17 hours in the group subjected to pulmonary bronchial artery flushing demonstrated leukocyte counts similar to those of intact lungs (45 +/- 5 versus 29 +/- 8/mm3) and significantly less than in lungs subjected to pulmonary or bronchial artery flushing (137 +/- 18 or 82 +/- 10/mm3, respectively).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Intravascular missile embolization in childhood: report of a case, literature review, and recommendations for management.

A collective review of 20 cases of missile embolization among children (1961 to 1988) is analyzed, one case added, and guidelines for diagnosis and management are outlined. Causative agents were bullets (14 patients), pellets (5), and fragments (2). Their trajectory was arterioarterial (11), venovenous (5), paradoxical (4), and mixed (1). Diagnosis was suspected when an exit wound was absent and the foreign body was traced on regional x-ray. Embolization was predominantly to the legs, with a tendency for the left (5 of 8 cases). Upper extremity emboli were exclusively to the right. Only one of five cardiac entries required closure to control bleeding compared with four of six aortic. Embolectomy was performed in 16 patients. The overall mortality rate was 9.5%. Factors predicting a favorable outcome are early presentation, diagnosis, and intervention; location of cardiovascular entry and embolus site; and presence of soft tissue tamponade at entry wound. Although embolectomy for cerebral, asymptomatic pulmonary arterial, and silent venous emboli is controversial, universal agreement prevails regarding removal of systemic arterial as well as venous emboli that are potentially problematic.

Aorta↗
PubMed1990

Aerodynamic evaluation of crystalloid and colloid flush perfusion for lung preservation.

To assess the effectiveness of pulmonary perfusion we evaluated the lung mechanics of 36 canine lungs in an isolated perfused working lung (IPWL) model. Four groups of lungs (n = 9 each) were preserved by pulmonary artery flushing with either high-potassium colloid (UW), high-potassium crystalloid (EuroCollins', EC), low-potassium crystalloid control (lactate), or low-potassium substrate-enhanced crystalloid (RPMI) followed by 130 +/- 10 min of cold storage. Ventilation remained constant (TV 10 ml/kg at 14 breaths/min with 5 cm H2O PEEP). Assessed data included lung resistance (R), timed expiratory volume (EV0.3 sec as %TV), lung compliance (C), elastic work (Wel), and flow-resistive work (Wres). Immediately following storage, R and Wel were similar for all groups (16 +/- 3 cm H2O/liter/sec and 149 +/- 18 gm/min). UW preserved lungs were less compliant (1.5 +/- 0.1 X 10(-2) liter/cm H2O) and required more inspiratory work (Wres 5.8 +/- 0.8 gm/min) compared to the low-potassium crystalloid (Lactate) group (2.0 +/- 0.1 X 10(-2) liter/cm H2O and 3.4 +/- 0.6 gm/min, respectively, P less than 0.05). For 3 hr of reperfusion, crystalloid lungs showed no significant change in R, C, Wel, or Wres. In contrast, R of the UW group increased significantly to 32 +/- 5 and 40 +/- 8 cmH2O/liter/sec at 1 and 3 hr, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

A method of decreasing anastomotic leaks and delivering cardioplegia in aortic root replacement.

Ascending aortic root replacement is associated with a significant incidence of bleeding from composite graft to annulus anastomosis and from coronary to composite anastomosis. We describe a technique for composite graft to annulus and coronary to composite graft anastomoses with circular Teflon donuts. We also describe a method for delivery of antegrade cardioplegia that allows assessment of anastomoses prior to weaning from bypass.

Anastomosis, Surgical↗